This invention relates to a feed nozzle for a furnace and more particularly to a plasma feed nozzle for a cupola. As described in U.S. Pat. No. 4,530,101 by M. G. Fey and T. N. Meyer, heat from an electric arc can be fed into a cupola or other furnace to enhance the operation thereof by providing a very hot gas stream which may be either oxidizing or reducing and can also be mixed with particulate material. The electric arc is produced in a plasma torch in which the electric arc ionizes the gas which is blown out of the end of the torch producing a white hot gas stream which generally operates in the range of 10,000.degree. F. or 5,538.degree. C. Such temperatures are maintained for hours or days in a relatively small diameter feed nozzle without destroying the refractory material which line the nozzle. Refractory material normally begins to soften about 2,900.degree. F. or 1595.degree. C. about one-third of the temperature of the superheated gas stream from the plasma torch.
Particulate material fed into the superheated stream melts rapidly providing expeditious rapid changes to the chemistry of molten metal in a cupola or other type of furnace.